1. Field of the Invention
This invention relates generally to air valves, and more particularly, to solenoid controlled, pilot operated air valves, such as four-way valves, three-way valves, two-way valves and the like for use in controlling the flow of pressurized air to and from various apparatuses such as, a press clutch, an air brake, an air cylinder, or any other device requiring speedy control of large volumes of operating air.
2. Description of the Prior Art
It is known in the air valve art to provide solenoid controlled pilot operated valves such as four-way valves, three-way valves, two-way valves and the like. A problem encountered in such prior art valves is that the shifting characteristics of the valves are not constant, because of fluctuations in the pilot air supply when the pilot air is supplied from the main air supply for such a valve. An example of a prior art valve employing an accumulator in the pilot air supply is shown in U.S. Pat. No. 3,238,972. A disadvantage of the accumulator system disclosed in said U.S. Pat. No. 3,238,972 is that the restricted orifice in the internal supply passage does not permit a fast flow of a full supply or volume of air into the accumulator system when a demand for a large volume of air is made on the accumulator. Another example of the use of an accumulator in a valve control system is illustrated in U.S. Pat. No. 3,119,308. The use of an accumulator in a time delay valve is also shown in U.S. Pat. No. 3,256,906.